Heating energy

Among all public buildings, on account of their educational purpose, school buildings have a major social responsibility. Therefore energy performance in this type of building is of great importance. The overall purpose of this research is to achieve a functional benchmarking, based on the real operation conditions of school buildings, by the exploitation of the results made public, through an intensive literature survey on energy consumptions in schools. The survey was made to gather data that is relative to energy consumption in school buildings, documented in the most diverse fields and units: global energy consumption values, electrical energy consumption; fuel consumption for heating, energy data consumption of schools expressed in annual cost per unit of heated/cooled surface area ($/m 2) or per unit of heated/cooled volume ($/m 3) or, finally, as the annual cost per student ($/student). The literature was analyzed to determine if a worldwide comparison among the published data could be established. The results suggest that when attempting to determine an energy benchmark some considerations should not be forgotten: standard indoor environmental conditions (IEC) for classrooms (set-point for indoor operative temperature of 20 1C in winter and 26 1C in summer as suggested in EN 15251:2007), electrical and heating consumption values should be kept separately, different education levels usually require different energy consumption values. A good way to normalize heating energy consumption is going through a climatic adjustment based on Heating Degree Days (HDD). For an impartial data comparison, based either on an operating rating or on a simulation carried out for reference conditions, benchmark reference values should be expressed in terms of billed energy data.

Educational buildings are buildings with special social importance and their energy consumption requires particular attention. Since the majority of educational buildings in Serbia were built between 1950-1990, with concrete frame, brick walls and poor thermal insulation, it can be concluded that these buildings have relatively high potential for thermal energy savings. In this paper, specific heat consumption of educational buildings (42 different institutions classified throughout educational levels) in the city of Kragujevac (Serbia) was analysed in order to determine their specific heat consumption (per heated floor area and per user) and to list the priorities for refurbishment. According to educational level, they were classified in: preschool buildings, elementary and high schools and faculties (university buildings). Data about heat energy consumption were collected during several heating seasons in order to minimize the influence of seasonal climate variations. Values of specific heat energy consumption of the buildings were benchmarked with data on specific heat consumption of schools from different European countries. In order to accomplish the tasks, authors introduced the concept of weather normalised specific heat consumption. Results of the performed analysis pointed out preschool and elementary school buildings as refurbishment priorities since their average specific heat consumption is the biggest (186 kWh/m 2 /a and 176 kWh/ m 2 /a, respectively). Besides, normalised specific heat consumptions of the educational buildings in Kragujevac are higher than in comparing countries and the potential for their energy efficiency improvement is significant.

Considered the main sources and types of signals that occurred during the operation of the thermotechnical equipment. Developed the generalized structure of intellectual multilevel distributed system of monitoring and diagnosis of thermotechnical equipment, which is consistent with the principles of the concept of "intelligent networks" Smart Grid.

The performance evaluation of a dual flat-plate solar thermal collector suitable for diurnal heating and nocturnal cooling applications is presented. Two collectors, each with estimated area of 0.784 m2 were designed, developed and experimentally investigated. The plates were made with mild steel and coated with matte black and polyethylene terephthalate (PET) powder. The results obtained showed that in the diurnal heating mode, the hybrid plate attained a maximum temperature of 68.8oC while the ambient temperature ranged from 25.3oC-30.4oC, at a peak insulation of 937.3W/m2during the test period. In the nocturnal cooling phase, the hybrid plate attained a minimum temperature of 21.3oC, while the ambient temperature ranged from 23.4oC-24.3oC. During the nocturnal phase at clear sky, the maximum water temperature drop recorded was about 10.3oC. Also,8oC difference in temperature occurred between the top water zone and the bottom zone in the tank, signifying a clear thermal stratification in the tank. The overall performance of the system revealed that the device is a promising technology in locations that have similar climatic conditions as Owerri; thus, showing a dual-purpose seasonal adaptability and energy saving capabilities. Therefore, an installation of the device into a building can ensure a supply of domestic hot water for domestic and other activities all year round. The system can also deliver heat for comfort heating in cold seasons or for comfort cooling during periods of elevated ambient temperatures, hence offsetting the seasonal energy bills in a building.

Ample literature is available on design of solar systems. However the energy conversion efficiency is about 10%. Nearly 80% of the incoming solar energy is either reflected or absorbed as heat energy. It is expected that the efficiency of conversion is improved by using Nano-fluids in the flat plate solar collector system. An attempt is made in this paper to fabricate and to study the effect of different nano particle concentrations in water as base fluid. Nano particles of TiO2 are tried. Different particle concentrations ratios were chosen for testing. It has been observed that the thermal efficiency of solar flat plate collector has been improved by 30% using nano fluids in the water base fluid. The major contribution of the present work is to design and analyze the effect of adding the nano particles in the water base on the thermal efficiency of the solar water heaters. It has been observed that there is nearly 30% rise in the efficiency of the solar flat plate water heaters by using nano Particles.